I cannot profess to know why ketogenic diets are the flavor of the week, other than the fact that there always is one of those- ever in the interest of those selling them, and almost never in the interest of those buying. There is some fairly new, and quite rudimentary research on the topic that might be the reason for the current infatuation, but the pop culture claims are wildly at odds with those data, to say nothing of the overall weight of scientific evidence regarding diet and health.
Whatever the reasons, legions seem poised to toast 2017 goodbye and welcome 2018 with ketogenic Kool-Aid, and I consider them dangerously mistaken. Before you join their misguided ranks, I suggest we drain this topic to its low-carb dregs and see where it leaves us.
The historical case for ketogenesis- denying the body its customary fuel sources so that glucose is in short supply, and instead it metabolizes fat preferentially, and generates ketone bodies as fuel- resides in starvation. Rather predictably, starvation has profound effects on all aspects of metabolism. The body effectively turns to auto-digestion to sustain itself during a protracted fast. Fat and protein stores in the body are converted to fuel, and metabolism then does run on ketone bodies.
In this modern age of epidemic obesity and type 2 diabetes, starvation has acquired a patina of merit. During starvation, blood sugar falls. Blood insulin falls. Blood cholesterol falls. Blood pressure falls. Weight declines. None of these were desirable throughout most of humanity’s subsistence, but all cry out “benefit” in this era of disease-by-excess.
But, alas, starvation has its drawbacks, among them the tendency to be fatal. When the body auto-digests, it is somewhat indiscriminate, and proteins can be leached even from vital organs such as the heart. That can disrupt micro-architecture, which can in turn disrupt electrical signaling, and that can and does cause fatal dysrhythmias. The first attempt to mimic the “benefits” of starvation medically, and thus arguably the fist ancestor to the current fixation on ketogenesis, was very low calorie liquid diets(VLCDs). These had the same drawback as actual starvation- periodic death by dysrhythmia- and have long since taken their place in the dust bin of bad ideas.
Starvation, then, is a dubious proposition- but the appeal of its metabolic advantages in modern context persists. This tension has propagated an on-going quest to secure the metabolic advantages of starvation without the pesky inconveniences of actually starving, and risking sudden cardiac death. The initial successful result of this effort was calorie restriction, or CR, or in another variant, the protein-sparing modified fast.
CR reduces calories to a level that imposes many of the effects of starvation. However, CR involves the very careful delivery of essential nutrients- including key proteins- so that the body does not auto-digest its own vital organs (hence, “protein sparing”). CR, like starvation, is ketogenic- achieving that effect not by restricting carbohydrate, but by restricting total calories. Most approaches to CR are, in fact, ketogenic despite being high in total carbohydrate from particularly nutrient-rich foods: notably vegetables, fruits, beans, and legumes. A primary principle of CR is to compensate for low-calorie intake with reliance on the foods richest in valuable nutrients.
CR is associated with certain liabilities, such as infertility, but appears to enhance longevity. This is clear in many species other than our own, and suggested for our own. But, CR involves something akin to “gentle starvation” every day, so there is a joke about it: maybe it makes you live forever, or maybe it just feels like forever!
This, then, is where the New-Age idea of ketogenic diets was incubated. The current hope is to have your CR benefits, but eat those calories, too. By restricting all carbohydrate sources, the body can be forced to run on ketone bodies even in the absence of semi-starvation.
There is a very serious problem with this concept, however, before we turn to the matter of evidence. The ketogenic diet idea makes the huge leap of faith that ketone bodies per se can confer health benefit. The work the idea is born from, however, establishes nothing of the sort. Starvation involves not just ketone bodies, but starvation- and is overall a very bad idea for the health-conscious. CR might be a good idea, at least for health-conscious masochists, but its benefits are decisively linked to low-intake of calories and high-intake of nutrient rich plant foods; ketone body generation just comes along for the ride.
What evidence is there that CR can be replaced with carbohydrate restriction; that nutrient-rich plant foods can be mostly or entirely displaced by meat – and the health or longevity benefits of CR, themselves less than entirely proven, replicated? To the best of my knowledge, in humans- absolutely none. Zero. The one known benefit of ketogenic diets is for the short-term control of otherwise intractable seizures, mostly in certain children.
There are, as noted, short-term studies of ketogenic diets showing the usual metabolic benefits attached to almost any diet replacing the prevailing state of ingestive anarchy with some kind of discipline: reduced blood sugar, blood cholesterol, blood pressure, and weight. But lest you think short-term improvements in these markers a good idea makes, consider these other “interventions” that do the same: a bout of cholera, a crack cocaine binge, the spread of cancer through one’s body, or the advance of tuberculosis. The historical name for tuberculosis, “consumption,” connotes exactly such effects; the infection eats away at you. Many life-threatening diseases evoke auto-digestion, and cause weight, cholesterol, glucose, insulin, and blood pressure to fall. They are all emphatically ill-advised just the same.
Perhaps the currently popular approach to ketogenic diets is a case apart, but the burden is on those making the claim to prove it- not on the rest of us to disprove it. They have a steep hill to climb. We have reason to wonder if the short-term “consumption” of ketogenesis turns into all the perks of a wasting disease over time for those rare individuals who can stick with it.
There is, for starters, no evidence that ketogenic diets are conducive to, or even compatible with, human health across the lifespan, or longevity. There is, instead, bountiful evidence that the very foods such diets exclude are associated with less diabetes, cancer, heart disease, dementia, and premature death in general. There is as well the experience of free-living populations. To date, every population group around the world found to experience remarkable vitality and longevity has a dietary pattern in which whole, nutrient-rich plant foods predominate, the very opposite of ketogenic. Vitality and longevity even in the last of the planet’s hunter-gatherers, or foragers, is similarly linked to a plant-predominant, high-carbohydrate diet.
So, OK, ketogenic diets might help people live long and prosper, but there are, to date, no such people. Admittedly, the Inuit, for want of choice, have a very low-carbohydrate diet which may at times be ketogenic, but they do not experience enviable health or longevity.
There is, as well, the inconvenience factor of being on a “diet” for the rest of one’s life. The argument for ketogenic diets reeks of fad, because like all fad diets, the benefits derive from eliminating most of the foods most people around the world like to eat. If ever there was a case of “fool me once, shame on you, fool me 10,000 times, shame on me,” the marketing of the next diet fad is surely it.
Arguments for ketogenesis as anything other than the next batch of Kool-Aid brewed specially for suckers need to navigate past all such impediments. There is more, however. While such diets are likely to be harmful to the health of people, they are certain to be devastating to the fate of the planet. The clamor for ketogenic diets is at odds with every trend necessary to preserve our aquifers, wild places, biodiversity, and climate.
So, maybe a diet low in vegetables, fruits, whole grains, beans, lentils, nuts and seeds; a diet low in antioxidants and phytonutrients, and devoid of fiber- could be good for you in spite of it all. If you are reaching for your credit card accordingly, you should understand you are paying for the privilege of making a leap of faith. Time will tell about the landing.
As for those peddling the concept of ketogenic diets so absurdly beyond the basis for it in any evidence, there are only two explanations. Either they have drunk deeply of their own low-carb Kool-Aid, and are themselves deluded; or they are selling the stuff to you, but know not to buy it, in which case they are profiteering hypocrites. The expansive market for fatuous diets provides abundant cover for both species.
As I write this, the proposed “Guiding Principles” for healthy eating in Canada have just been released. They are eminently sensible, current, and evidence-based; so naturally, they are under immediate attack, as was the comparably sensible 2015 report of the Dietary Guidelines Advisory Committee here in the U.S. before ever its ink was dry. The beef and dairy industries oppose the movement toward more whole-food, plant-predominant diets so decisively associated with better health outcomes for people and planet alike. They would be more than glad to toast 2017 on its way with ketogenic Kool-Aid.
The likelihood, however, that they are toasting to your good health in 2018, let alone that of the planet, is very remote indeed. I do so, wishing you a happy New Year, and the boon of prudent choices.
Author disclosure statement: A recent, provocative article in JAMA called on all scholars addressing diet to disclose their own position, practice, and interests. Accordingly, I note that I am a life-long advocate of minimally processed, plant-predominant diets on the basis of relevant evidence I have reviewed directly. I practice such a diet personally. I do not have a financial interest in any specific kind of diet, but I do inevitably have a financial interest in advancing what I consider to be the truth about diet and health, since all of my professional activities are devoted to that mission.
Director, Yale University Prevention Research Center; Griffin Hospital
Immediate Past-President, American College of Lifestyle Medicine
Senior Medical Advisor, Verywell.com
Founder, The True Health Initiative